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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=au15CuIx; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 741B3606B582; Fri, 13 Nov 2026 12:08:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=au15CuIx Received: by smtp.kernel.org (Postfix) with ESMTPSA id 947EF1F000C4; Fri, 13 Nov 2026 12:08:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794571728; bh=DCPKKvSKsZGN6ZGZTx2lYYqlAtYoJoEa/WryVTu5l4E=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=au15CuIxjBQb5zBlCDyGEp8bBtB0P5Q1riTnaoMRjIfwb8D+lUqZY7XXgl0RsxAzE kEueU9MSfS09y0CdiKoR78LXqvmC+g1NN+S7+0AXg5mE3c7yxaFGCFPasTn7U4P2Yq wCOmTQgCrhEq4vvUSftMSYa5B30cDjtQSZ4QKKgcyn3VBZTG1A+Enp95W85ZAMdrq6 O7g68nfE/V7ai7AnS5L0FgWFeW+jFuPUAjGijxYYKQwiRFrELWdqd1vF1K1M2iFOMJ /QMc3+6yubESduWY8XFoIkDyAQVIKCBMJaq+EJ2OJhCHuSIlaa63VHGiH5duiMEZum aurui0ZOLZ9TA== Message-ID: Date: Fri, 13 Nov 2026 13:08:35 +0100 X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 1/5] iommu/dma: Keep reserved regions below the IOVA rbtree anchor To: Vikash Garodia , "Joerg Roedel (AMD)" , Vasant Hegde , Suravee Suthikulpanit , Will Deacon , Robin Murphy , David Woodhouse , Lu Baolu , Jean-Philippe Brucker , Rob Herring , Saravana Kannan , Tomasz Nowicki , Eric Auger , Bryan O'Donoghue , Joerg Roedel , Srinath Mannam , Oza Pawandeep , Lorenzo Pieralisi , Bjorn Helgaas , Alex Williamson Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, devicetree@vger.kernel.org, kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org, Sashiko , stable@vger.kernel.org, Vishnu Reddy References: <20261106-add_iommu_ranges-v7-0-5c0f72083e52@oss.qualcomm.com> <20261106-add_iommu_ranges-v7-1-5c0f72083e52@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/11/2026 18:14, Vikash Garodia wrote: > The IOVA allocator tracks address ranges by page frame number (PFN). > The highest node in its rbtree is a fixed anchor at PFN ~0UL, which is > embedded in the DMA cookie. dma-iommu converts reserved regions to PFNs > with iova_pfn(), which returns unsigned long. On x86-32 with PAE, > addresses are 64-bit but unsigned long is 32-bit, so the upper bits of > the PFN are lost. > A reserved region that ends at the top of the address space then gets > the anchor's PFN. reserve_iova() merges it into the anchor and lowers > the anchor's pfn_lo. At teardown, free_iova_mem() no longer recognises > the anchor and frees it to iova_cache, which corrupts the slab. PCI host > bridge windows above 16TiB and the reservation after the last PCI DMA > window hit the same problem. > Compute the PFNs in u64. Skip ranges that start above the PFN space and > clamp the end one PFN below the anchor. The allocator never hands out > those IOVAs, so nothing is lost. On 64-bit, PFNs never reach ~0UL, so > nothing changes there. > > Fixes: fade1ec055dc ("iommu/dma: Avoid PCI host bridge windows") > Fixes: 7c1b058c8b5a ("iommu/dma: Handle IOMMU API reserved regions") > Fixes: aadad097cd46 ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA address") > Reported-by: Sashiko > Closes: https://lore.kernel.org/all/sashiko-outbox-195658@kernel.org/ > Cc: stable@vger.kernel.org > Co-developed-by: Vishnu Reddy > Signed-off-by: Vishnu Reddy > Signed-off-by: Vikash Garodia > --- > drivers/iommu/dma-iommu.c | 32 ++++++++++++++++++++------------ > 1 file changed, 20 insertions(+), 12 deletions(-) Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof